Cadmium levels in Ontario moose and deer in relation to soil sensitivity to acid precipitation.

This study examines the influence of buffering capacity of the soil on the levels of cadmium in the kidney, liver and muscle of moose and white-tailed deer from nine sampling sites (four buffered and five non-buffered) in Ontario, Canada. Tissues collected from hunter-killed moose and deer during 1984 and 1985 were analysed for cadmium. Tissue from moose in the non-buffered Algonquin Park site (21.9 +/- 1.1 mg/kg wet weight) and the buffered St. Joseph Island site (12.7 +/- 3.2 mg kg-1) had the highest mean levels of kidney cadmium compared with other sites sampled in Ontario. The highest mean levels of kidney cadmium in deer were found in the non-buffered Loring site (15.1 +/- 0.8 mg kg-1) adjacent to Algonquin. From all sites, the level of cadmium was highest in kidney, lower in liver and was often undetectable in muscle. Cadmium level increased with animal age (p less than 0.05). Levels of cadmium in Ontario moose from some regions are comparable to those found in Quebec and Manitoba and are considerably higher than those of Maine and Scandinavia. Levels of cadmium in kidneys and livers of white-tailed deer in parts of Ontario are considerably lower than those in Pennsylvania. As a result of this study, the Ontario Ministry of Natural Resources, in consultation with the Ontario Ministry of Health, has recommended that the public not consume kidneys or livers of Ontario moose and deer.

The fate and impact of oil and oil-dispersant mixtures in freshwater pond ecosystems: introduction.

Oil and oil-dispersant mixtures were added to the surface waters of a series of man-made ponds. The fate of the oil and dispersant (Norman Wells crude and Corexit 9527 respectively) were studied as well as the impact of the added chemicals on the ponds' ecosystems. Elements of the ecosystems studied include bacteria, fungi, phytoplankton, periphyton , proto- and mesozooplankton , zoobenthos and surface insects. In addition a number of water quality parameters were regularly monitored. Comparisons were made between oil-treated and control ponds, as well as oil-dispersant treated and oil and/or control ponds. This paper describes the experimental set up and provides a summary of the findings reported in the following five papers.

Impact of oil and oil-dispersant mixtures on flora and water chemistry parameters in freshwater ponds.

Oil and oil-dispersant mixtures at nominal concentrations of 100 and 20 ppm, respectively, were added to a series of ponds constructed for the study. In the pond treated with oil, there were no discernible short or long term effects on the phytoplankton. Both oil-dispersant treated ponds exhibited fluctuations in the dominant class of algae while the concentration of oil was greater than in the water column. Once the oil concentrations were below this value, there was no apparent effect. Periphytic material on the sides and bottoms of the oiled and control ponds were similar in mass and composed of a large number of species. Periphyton biomass was at least three times greater in both oil-dispersant-treated ponds with one genus dominating the growth. These conditions persisted in one of the oil-dispersant-treated ponds one year after treatment but those in the other pond had decreased to levels in the control pond at this time. Dissolved oxygen (DO) values decreased to about 4.6 ppm in both oil-dispersant-treated ponds shortly after treatment, but remained at approximately the saturation level in the other ponds for 6 weeks after treatment. Then these lower values gradually increased until they were slightly greater than in the controls. During the late winter months, both oil-dispersant ponds had anoxic zones above the sediment, the extent depending on the contours of the bottom. The DO values in the other ponds were at the saturation level. In the early spring, the nitrate ion-concentrations in control and oil-treated ponds were twice those measured for the oil-dispersant ponds. No discernible differences dependent on treatment were observed for nutrients or other ions monitored on a regular basis.